Surfactants have wide performances such as emulsification, dispersion, cleaning, wetting and foaming. By utilizing those performances, they are conventionally used in preparing products such as paints, printing inks and adhesives, and are contained in products as components that are indispensable in stabilization of products, workability and the like. Particularly, in recent years, a movement toward high performance of end products using a surfactant is becoming active. Accordingly, deterioration of performances such as water resistance of coating films, printing surfaces, adhesive coatings, and the like due to surfactants is pointed out.
As an emulsifier for emulsion polymerization, for example, use has been made conventionally of anionic surfactants such as soaps, sodium dodecylbenzene sulfonate, a polyoxyethylene alkyl phenyl ether sulfuric ester salt and a polyoxyethylene alkyl ether sulfuric ester salt; and nonionic surfactants such as polyoxyethylene nonyl phenyl ether and a polyoxyethylene alkyl ether are utilized. However, in polymer films obtained from polymer dispersions using those emulsifiers, the emulsifiers used remain in the polymer films in a free state, and therefore there is a problem that water resistance and adhesiveness of films are deteriorated. Furthermore, even in polymers produced by suspension polymerization, the similar phenomenon due to a dispersant for suspension polymerization is pointed out. Therefore, many reactive surfactants having a copolymerizable unsaturated group have been proposed as an improvement measure against the above problems (for example, Patent Documents 1 to 3).
However, reactive emulsifiers having an acryl group or methacryl group as a copolymerizable unsaturated group that are proposed in the conventional arts have excellent copolymerizability with a monomer, but have a problem that polymerization stability during emulsion polymerization is deteriorated. For example, there are problems such that the amount of aggregates during emulsion polymerization is large, particles formed are coarse and stability with time is poor. Reactive emulsifiers having an allyl group as a copolymerizable unsaturated group sometimes have poor copolymerizability between the reactive emulsifiers and monomers depending on monomer species and polymerization conditions, and a polymer film obtained by a polymer dispersion remains the problem that one capable of sufficiently satisfying water resistance and adhesiveness cannot be obtained and the problem that process trouble is caused from foaming of the polymer dispersion. Particularly the above problems frequently occur in the case of containing styrene as a monomer in emulsion polymerization, and improvement of those problems are strongly demanded in commercial production.